linux-kernel - Re: [PATCH] irqchip/gic-v3-its: Skip HP notifier when no ITS is registered

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Date:   Wed, 2 Feb 2022 04:40:05 -0600
From:   Steev Klimaszewski <steev@...i.org>
To:     Marc Zyngier <maz@...nel.org>, linux-kernel@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>, kernel-team@...roid.com,
        Valentin Schneider <valentin.schneider@....com>
Subject: Re: [PATCH] irqchip/gic-v3-its: Skip HP notifier when no ITS is
 registered


On 2/2/22 4:34 AM, Marc Zyngier wrote:
> We have some systems out there that have both LPI support and an
> ITS, but that don't expose the ITS in their firmware tables
> (either because it is broken or because they run under a hypervisor
> that hides it...).
>
> Is such a configuration, we still register the HP notifier to free
> the allocated tables if needed, resulting in a warning as there is
> no memory to free (nothing was allocated the first place).
>
> Fix it by keying the HP notifier on the presence of at least one
> sucessfully probed ITS.
>
> Fixes: d23bc2bc1d63 ("irqchip/gic-v3-its: Postpone LPI pending table freeing and memreserve")
> Reported-by: Steev Klimaszewski <steev@...i.org>
> Signed-off-by: Marc Zyngier <maz@...nel.org>
> Cc: Valentin Schneider <valentin.schneider@....com>
> ---
>   drivers/irqchip/irq-gic-v3-its.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index 9e93ff2b6375..cd772973114a 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -5517,6 +5517,9 @@ int __init its_lpi_memreserve_init(void)
>   	if (!efi_enabled(EFI_CONFIG_TABLES))
>   		return 0;
>   
> +	if (list_empty(&its_nodes))
> +		return 0;
> +
>   	gic_rdists->cpuhp_memreserve_state = CPUHP_INVALID;
>   	state = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
>   				  "irqchip/arm/gicv3/memreserve:online",

Tested on the Lenovo Yoga C630

Tested-by: Steev Klimaszewski <steev@...i.org>